DESCRIPTION: (provided by the applicant): Malaria kills over one million persons every year. Because current intervention procedures with drugs, insecticides and vaccines are ineffective, new approaches for malaria control are urgently needed. Malaria transmission depends on the ability of the Plasmodium parasite to develop in the mosquito vector. However, at the molecular level, very little is known about the complex developmental program that governs Plasmodium differentiation in the mosquito. The proposed project seeks to reduce this knowledge gap. Initial experiments conducted in this laboratory have assembled many of the required tools for the project. Four cDNA subtraction libraries have been constructed that are enriched for sequences expressed at different stages of Plasmodium development in the mosquito. Micro-arrays containing 4,000 clones are being produced and over 2,000 inserts are being sequenced. Using these tools, Plasmodium genes that are preferentially expressed at specific stages of development in the mosquito (and not in the vertebrate host) will be identified and selected for further study. Particular attention will be devoted to genes encoding proteins with transmembrane domains (candidate receptors and transmission-blocking antigens) or that have motifs suggesting involvement in regulatory functions (e.g., signal transduction, kinase domains, similarity to transcription factors). Temporal expression of these genes will be investigated and antibodies will be produced to determine cellular localization. The possible ability of these antibodies to block development of the parasite in the mosquito will be assessed. Knockout mutations will be produced and changes of gene expression caused by these mutations will be measured by use of the micro-arrays.